Reclosable system for flexible packages having interlocking fasteners

ABSTRACT

A reclosable flexible package includes a reclosure having flanges joined at their upper ends to interlockable fastener tracks. The lower ends of the reclosure flanges are joined together with one of the reclosure flanges being joined to a side panel of the flexible package by a peel seal.

This is a division of prior application Ser. No. 10/174,614, filed Jun.19, 2002, now U.S. Pat No. 6,863,646, which is hereby incorporatedherein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to the closure of flexible packages, suchas plastic bags, and in particular to fastener closures employingsliders.

2. Description of the Related Art

With the recent emphasis in providing consumers with bulk quantities ofvarious commodities, such as food products, reclosable packages havebecome increasingly popular. One of the most popular means of providingreclosability is to employ zippers of various types, particularlyzippers which are compatible with flexible packages of plastic filmconstruction. Manufacturers of food products and other commodities areconcerned with filling the contents of a flexible package as quickly andeconomically as possible. It is important that the opening provided bythe fastener be made as large as practically possible. Consumers orother end users also prefer large sized openings for easy extraction ofproducts from the package interior. Even with large openings, however,products within the package may interfere with fastener operation whenproduct poured or otherwise dispensed from the package becomes entrainedin the fastener components.

Other improvements to flexible reclosable packages are being sought. Forexample, when handling products comprised of numerous small pieces, suchas shredded cheese or cereal, for example, it is generally desirable tohave the package formed into a pouch which is open at one end, or alongone side, so as to allow product to be poured or shaken through thereclosable opening. It is desirable that the product be allowed tofreely flow past the reclosable opening. Preferably, the path taken bythe product within the package should be made as smooth as possible.

Although improvements have been made in the art of plastic welding andjoining, manufacturers of consumer products employing high speedproduction techniques are continually seeking improved package formingmethods and equipment. Any reduction in the time needed to form theseand other package features can result in substantial cost savings.

Commercial package designs having zipper closures with peelable sealssuffer from a reduction of volume capacity compared to other types ofalternative packaging.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a reclosable plasticpackage having an optimized package volume.

Another object of the present invention is to provide a package of theabove type with interlockable fastener tracks, usable with or withoutslider members.

A further object of the present invention is to provide a plasticpackage of the above type suitable for use with a shroud enclosing theinterlockable fastener tracks.

These and other objects of the present invention are attained in areclosable flexible package, comprising a reclosable flexible package,comprising: opposed front and rear package panels having sides andjoined together to form an interior and a package opening communicatingwith said interior; first and second interlockable fastener tracksconfigurable in a closed position and an unlocked open position; saidinterlockable fastener tracks having opposed ends located adjacent saidopposed sides of said front and said rear package panels; a reclosurejoined to said first and said second interlockable fastener tracks,including first and second reclosure flanges having first ends joined tosaid first and said second interlockable fastener tracks, respectively;said first and said second reclosure flanges having a second end joinedto each other; one of said first and said second reclosure flangesjoined to one of said front and said rear package panels with a peelseal; first ends of said first and said second reclosure flanges joinedto respective ones of said front and said rear package panels; a sideseal of preselected width joining together one side of said front andsaid rear package panels; a slider movable along said interlockablefastener tracks to configure said interlockable fastener tracks in saidinterlocked position so as to close said opening and to configure saidinterlockable fastener tracks and said unlocked position so as to allowaccess through said opening to set package interior; and stops adjacentsaid ends of said interlockable fastener tracks to interfere with andprevent travel of said slider beyond said interlockable fastener tracks.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of a reclosable flexible package accordingto principles of the present invention;

FIG. 2 is a cross-sectional view taken along the line 2—2 of FIG. 1;

FIG. 3 is a fragmentary perspective view of a reclosure assemblythereof;

FIG. 4 is a top plan view thereof prior to welding assembly;

FIG. 5 is a top plan view thereof after welding assembly;

FIG. 6 is a cross-sectional view taken along the line 6—6 of FIG. 5;

FIG. 7 is a fragmentary perspective view showing a method of making thereclosable flexible package;

FIG. 8 is a fragmentary cross-sectional view taken along line 8—8 ofFIG. 7;

FIG. 9 is a fragmentary perspective view of a portion of FIG. 7;

FIG. 10 is another perspective view thereof; and

FIG. 11 is a cross-sectional view similar to that of FIG. 2, but showingan alternative reclosable, flexible package according to principles ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, and initially to FIGS. 1 and 2, areclosable, flexible package 10 has opposed front and rear packagepanels 12, 14 joined together to form an interior 16 and a packageopening adjacent the upper end of the package, communicating with thepackage interior. First and second interlockable fastener tracks 20, 22are configurable between a closed position and an unlocked openposition. Referring to FIG. 1, the interlockable fastener tracks haveopposed ends located adjacent sides of the front and rear packagepanels.

A reclosure 30 is joined to the interlockable fastener tracks 20, 22 andincludes fastener flanges 32, 34 joined to the interlockable fastenertracks. The reclosure 30 further includes reclosure flanges 40, 42 withupper ends attached to fastener flanges 32, 34 with a weld seal and withlower ends joined together by a weld seal 48. In the preferredembodiment, the reclosure flanges 40, 42 are covered with layers 50, 52of metalocene of other fusion-enhancing material. The upper, first endsof the reclosure flanges 40, 42 are joined to the front and rear packagepanels 12, 14 with a weld or fusion seal. The lower end of reclosureflange 40 is joined to package panel 12 by a peel seal 58.

In the preferred embodiment the reclosable flexible package 10 isillustrated with an optional shroud 62 formed as an extension of packagepanels 12, 14 and joined together with a dead fold 64. Laser scores 66extend along the shroud, and provide convenient separation of the shroudfrom the package panels, exposing the interlockable fastener tracks. Ifdesired, the shroud can be omitted. Also illustrated in the preferredembodiment is an optional slider member 70, portions of which extendthrough holes formed in shroud 62, as illustrated for example in FIG. 1.If desired, the slider member 70 can be omitted.

Referring now to FIGS. 3–6, construction of reclosure 30 is illustrated.Preferably, interlockable fastener tracks 20, 22 are provided withintegral fastener flanges 32, 34. A film body 76 extends between theinterlockable fasteners tracks and provides material for the reclosureflanges. The reclosure flanges are separated one from another by cuttingthe film body along cut line 78. Film body 76 is preferably severedalong line 78 after fastener flanges 32, 34 are joined to the outeredges of the film body by fusion seals indicated at 82, 84. Further, itis generally preferred that peel layer 58 is joined to the film bodyadjacent cut line 78. As illustrated in FIG. 3, film body 76 is providedwith metalocene layer 86 which, after severing along cut line 78, formsreclosure flanges 40, 42 illustrated for example in FIG. 2. Also, priorto cutting along line 78, a weakening line 92 is formed to one side ofpeel layer 58. The weakening line 92 may take any suitable form, butpreferably comprises a line of perforations.

FIG. 4 shows the preferred method of construction, with weakening line92 formed in film body 76, prior to joiner with the fastener flanges 32,34. If desired, the peel layer 58 can be provided either prior tojoining of the fastener flanges 32, 34 with the film body 76, or later,after the fastener flanges 32, 34 are joined to the film body 76 asshown in FIG. 5. A cross-section of the completed reclosure 30 isillustrated in FIG. 6.

Referring now to FIGS. 7–10, the preferred method of assembling thereclosable flexible package is illustrated. Preferably, the front andrear package panels and the optional shroud is provided as a continuousfilm sheet folded at its bottom end to form the dead fold 64. Thereclosure 30 is provided as a continuous sheet, attached to theinterlockable fastener tracks, as described above. Seal bars 102–108 areprovided to join the reclosure to the package panels. Preferably, theseal bars operate as opposed pairs, drawn together to press the filmcomponents of the reclosable, flexible package together, for desiredjoining. Seal bar 102 is maintained at a relatively low temperaturewhile the remaining seal bars 104–108 are maintained in a “hot”condition suitable for fusion seal formation. Opposed seal bars 102, 104cooperate together to form the fusion seal 48 between reclosure flanges40, 42 and the peel seal 58 formed between reclosure flange 40 andpackage panel 12.

During the sealing operation, a tool 110 is employed, in a mannerillustrated in FIGS. 7, 9 and 10. Tool 110 includes a body portion 112defining a vertically extending opening 114 communicating with ahorizontal opening 116 formed between cantilevered fingers 118 and 120.As can be seen for example in FIGS. 9 and 10, fingers 118, 120 receivecantilever support from body 112 and are terminated in free ends attheir downstream portion, relative to the direction of travel 124 of thereclosable, flexible package components.

Referring to FIG. 8, it can be seen that the “cold” seal bar 102 pressesagainst package panel 14 and upper finger 118 to provide backing supportfor the “hot” seal bar 104 which forms peel seal 58 between packagepanel 12 and reclosure flange 40, and fusion seal 48 between the opposedface of reclosure flange 42 and reclosure flange 42. The remaining pairof seal bars, “hot” seal bars 106, 108, form a fusion seal 124 betweenthe package panels 12, 14 and their respective reclosure flanges 40, 42.In FIG. 8, the fusion seals 48, 124 are schematically indicated forillustrative purposes, it being understood that the fusion seal isformed by direct contact of one film component to another withoutintervening seal material. It can be seen in FIG. 8 that finger 120 oftool 110 prevents unintentional fusion of flanges 42 and 40.

Referring to FIGS. 7, 9 and 10, it is generally preferred that thereclosure 30 be continuously mated with the package panels, for joiningin a continuous sealing operation. As illustrated, the reclosure flange42 passes through vertical opening 114 and horizontal opening 116 intool 110 such that the free end is presented for contact with reclosureflange 40, to form the fusion seal 48.

It can be seen that the method of assembly includes providing a toolmember 110 having a body portion 112 defining a vertical opening 114,generally normal to the direction of web travel. Tool member 110includes fingers 118, 120 extending in a generally horizontal directionand forming horizontal opening 116 therebetween, it being understoodthat the horizontal direction is the direction of web travel. One of thereclosure flanges is guided through the normally extending opening 114and the opening extending in the direction of web travel, 116 to bringthe free ends of the reclosure flanges together for fusion sealing. Inone aspect, the fingers 118, 120 provide backing support for the sealingoperations.

Turning now to FIG. 11, an alternative embodiment of a reclosable,flexible package is generally indicated at 1000. The reclosable,flexible package 1000 is substantially identical to reclosable, flexiblepackage 10 described above, except that reclosure flanges 40, 42 aredouble-faced with a metalocene or other fusion-enhancing outer layer. Ascan be seen from FIG. 11, the metalocene layers 500, 520 oppose eachother and, upon the application of tooling to carry out a fusionoperation, are joined directly together to form a fusion seal 48,indicated in FIG. 11. In the reclosable, flexible package 1000, there isan enhanced difference between the failure strength of fusion seal 48and the weakened portion 92, formed by perforation or other weakening ofreclosure flange 40 and the layers 50, 500 associated therewith.Accordingly, further assurance is provided that, upon a conventionalopening operation, internal components of the reclosable, flexiblepackage will separate in the desired manner, at the line of weakening 92and the peel seal 58. Thus, desired opening of the reclosable, flexiblepackage is further assured. As mentioned above, with reference to FIGS.1–10, it has not been found necessary to provide opposed, or inwardlyfacing fusion-enhancing layers on the reclosure tracks 40, 42. That is,direct fusion between the reclosure flanges 40, 42 at fusion seal 48 hasbeen found adequate in those applications to assure desired opening ofthe package at the line of weakening 92 and the peel seal 58 without theaddition of fusion-enhancing layers 500, 520.

As can be seen from the above, the reclosable, flexible packagedescribed above can be employed with interlockable fastener tracks withor without a slider feature. Preferably, the interlockable fastenertracks comprise interlocking profiles with integral heat seal flangesextending from each profile. Each flange of the interlocking fastenertracks is fusion sealed to a respective side panel of the flexiblepackage. A weakening line, preferably a perforation or a laser scoreline is located on the first reclosure flange, to one side of its fusedsection. A peelable layer is co-extruded onto the first flange adjacentthe line of weakening and on the side facing the adjacent side panel ofthe flexible package. The peel seal is made between the peelable layerand the flexible package panel. As seen, the two reclosure flanges arefusion sealed to each other at their free ends, at a point below theline of weakening, and opposite to the peel layer. The remaining, secondreclosure flange remains unattached to its adjacent side panel of theflexible package.

The present invention can be readily employed with various commerciallyavailable interlockable fastener tracks, sometimes referred to as“zipper” tracks. The present invention can be employed withinterlockable fastener tracks containing peelable layers on the interiorsurface of their fastener flanges. The present invention allows hermeticsealing of the flexible package below the interlockable fastener tracks,since the fusion seal of the exterior surface of the fastener flangesagainst the side panels of the flexible package are typicallyinsufficient to provide required hermeticity. Notably, the presentinvention solves a prevailing problem of reclosable fastener tracksreducing the volume capacity of the flexible package. Reduced volumecapacity results in higher material costs, slower filling speeds,inconsistent peel force to open the flexible package, and a reducedburst strength when the package is exposed to low barometric pressureconditions frequently encountered in high altitude warehousing anddistribution markets.

With reference to FIG. 2, it can be seen that the present inventionprovides an extra package interior volume indicated by reference numeral130, formed between reclosure flange 42 and the upper portion offlexible package panel 14. Accordingly, with the present invention,several additional advantages are obtained. For example, the volumecapacity of the flexible package for bottom filling operations isincreased to attain a competitive advantage associated with packagingsystems which do not employ peelable fasteners. The filling speed forbottom filling operations is increased by allowing product to reach thespace indicated by reference numeral 130 in FIG. 2, behind the peellayer at the deepest end of the fastener flanges (fastener flange 34 inFIG. 2). Further, the first opening of the flexible package isassociated with breaking the perforation 92 (shown for example in FIG.2) while the force to break the peel seal does not depend upon the widthof the peelable extrudate. If desired, the peelable extrudate may bereduced to a narrow line that provides a continuous hermetic seal acrossthe width of the flexible package. As a further advantage, the burststrength of the bag is increased because the stress point has moved fromthe peelable bond to the fusion bond between the reclosure flangeexterior layer and adjacent the side panel of the flexible package. Inother aspects, the present invention can be readily employed in theretrofit conversion of existing equipment to allow economical fitting ofthe tool member 110 shown for example in FIGS. 9 and 10.

The drawings and the foregoing descriptions are not intended torepresent the only forms of the invention in regard to the details ofits construction and manner of operation. Changes in form and in theproportion of parts, as well as the substitution of equivalents, arecontemplated as circumstances may suggest or render expedient; andalthough specific terms have been employed, they are intended in ageneric and descriptive sense only and not for the purposes oflimitation, the scope of the invention being delineated by the followingclaims.

1. A reclosable flexible package, comprising: opposed front and rearpackage panels having sides and joined together to form an interior anda package opening communicating with said interior; first and secondinterlockable fastener tracks configurable in a closed position and anunlocked open position; said interlockable fastener tracks havingopposed ends located adjacent said sides of said front and said rearpackage panels; a reclosure joined to said first and said secondinterlockable fastener tracks, including first and second reclosureflanges having first ends joined to said first and said secondinterlockable fastener tracks, respectively; said first and said secondreclosure flanges having second ends joined to each other; one of saidfirst and said second reclosure flanges joined to one of said front andsaid rear package panels with a peel seal; first ends of said first andsaid second reclosure flanges joined to respective ones of said frontand said rear package panels; a side seal of preselected width joiningtogether one side of said front and said rear package panels; a slidermovable along said interlockable fastener tracks to configure saidinterlockable fastener tracks in said interlocked position so as toclose said opening and to configure said interlockable fastener tracksin said unlocked position so as to allow access through said opening tosaid package interior; and stops adjacent said ends of saidinterlockable fastener tracks to interfere with and prevent travel ofsaid slider beyond said interlockable fastener tracks.
 2. The reclosableflexible package of claim 1 further comprising a shroud covering saidslider and at least a major portion of said interlockable fastenertracks.
 3. The reclosable flexible package of claim 2 further comprisingweakening portions extending adjacent said interlockable fastener tracksfor severing of said shroud in preparation for removal of said shroudfrom the remainder of said reclosable flexible package.
 4. Thereclosable flexible package of claim 2 wherein said shroud covers thesubstantial entirety of said interlockable fastener tracks.
 5. Thereclosable flexible package of claim 2 wherein said shroud definesopenings for said slider.
 6. The reclosable flexible package of claim 1wherein said one of said first and second reclosure flanges joined toone of said front and said rear package panels with a peel seal has aweakened area between said peel seal and said first end of said one ofsaid first and said second reclosure flanges.